Read the given extract/source/passage carefully and answer the question that follows:

Other than these seven parties, most of the major parties of the country are classified by the Election Commission as ‘State parties’. These are commonly referred to as regional parties, Yet these parties need not be regional in their ideology or outlook. Some of these parties are all Indian parties that happen to have succeeded only in some states, Parties like the Samajwadi Party and Rashtriya Janata Dal have national-level political organisations with units in several states. Some of these parties like Biju Janata Dal, Sikkim Democratic Front, Mizo National Front and Telangana Rashtra Samithi are conscious of their State identity.

Over the last three decades, the number and strength of these parties have expanded. This made the Parliament of India politically more and more diverse. No one national party was able to secure a majority in the Lok Sabha, until 2014. As a result, the national parties are compelled to form alliances with State parties. Since 1996, nearly every one of the State parties has got an opportunity to be a part of one or the other national-level coalition government. This has contributed to the strengthening of federalism and democracy in our country.

What made the Parliament of India politically more and more diverse?