During the elections, political parties bring out their manifestos. Generally, what percentage of the manifesto is fulfilled once the party comes to power?

Generally very little.  These books are mostly platitudes and very infrequently read, I would guess.  I've bought a few myself—those of Howard Dean, Barack Obama (I'm talking about The Audacity of Hope, not Dreams from my Father), John McCain, and Mitt Romney.  Of those, only one has actually made it to the White House.  All of the books have gathered dust and I never actually read them (I read Dreams from my Father, but that was a memoir, and I didn't read the more polemical work). Regardless, most of the goal of these books are preaching to the choir and trying to motivate your base rather than articulate policy that you'll actually spearhead.  It's important to remember that Congress has the primary responsibility to craft legislation, not the president.  It seems largely that the era from Wilson to FDR shifted the emphasis in making the president a policy maker rather than a simple executive for the existing laws.  The Constitution still structures the government in a manner that is aimed to Congress doing that work.  As such, unless the president has large majorities in both houses, there's little he can do. Interesting note here: even when Obama did have a large majority in both including briefly a supermajority in 2009, his main "accomplishment" was a piece of legislation that he campaigned against in the primary fight with Hillary Clinton.

Perhaps the whole concept of a "Political Agenda" in India is a complete Fugazi. As bodacious as it might look, the creators since the inception concentrate on a single factor -> How to gather maximum votes (Keeping in mind all castes and creeds, offcourse). Once they win to become the ruling party, the first half of their tenure goes away in fulfilling the most obvious and simplest of points mentioned in their agenda and in the second half, some work of a major significance which is achievable is taken up. Towards the end, PR companies are hired and asked to porpogate all the minimal work done by the party. The people do vote the party to power, but rarely know what is good for the country. They (We in that case) just have the power to vote, imagine and wait. On the contrary, national interest might lie somewhere else which is why sometimes false promises have to be made to win the public's heart and once in power the government can do what is "really" good for the people. Well I'd say that fulfillment of promises has been quite unimpressive until now. Most of it is just rhetoric during the election campaigns and once the party is voted to power, it either unabashedly goes back on it's word or defends its actions with some ambiguous legal argument.

I found a discussion on awaremonk which says this- http://awaremonk.com/user/singlePost/55307 Ideas of Democracy are embedded in accountability. A manifesto, hence serves as an important benchmark for analyzing the performance of a government and ensuring it's accountability to the electorate with regards to the policies and promises envisioned in the document. Manifestos have since time immemorial been a very essential document of political organizations as meaningful sources of information and data pertaining to a party's stance on a wide range of developmental issues. It would be prudent to remember though, that in an effort to acquire power, manifestos can often be contain lofty ideals and unrealistic agendas. The boundaries between polity and national aspirations are becoming blurry in many of the manifestos being published. A manifesto is a significant text worthy of consideration in a democratic dispensation, however it is reasonable to state that when agendas for development are colored in political hues, it becomes tough for succeeding governments to seek validation of their motives by using the ideals enshrined in a document, even if the issues raised had an over-arching theme of national importance.