As of today, there are a total of 1910 tokens and coins listed on Coinmarketcap.com. Out of this total list, only 496 coins are mineable coins and tokens. These coins have a total market cap of $181 Billion (as of 2nd Sept 2018); needless to say, Bitcoin leads the pack with $124 Billion. Probably a 100 different coins have started their operations in the past 2 years.
The list of the top 50 mineable coins are provided here sorted on their market capitalization on 2nd Sept 2018. The full list of 496 coins is available here.