For the second straight week, fewer people are playing games made by Zynga, the Facebook gamesmaker best known for Farmville.

The chart below, compiled by Lou Kerner of SecondShares.com, shows consecutive weeks of decline in the number of unique users on Zynga games over the prior 30 days.

Part of the reason for the decline is that Facebook has limited the number and type of "notifications" Zynga and other gamesmakers can send players. These limits, and Facebook's insistence that gamesmakers use its expensive payment system, have Zynga looking to host its games elsewhere.

Follow the Chart Of The Day on Twitter: www.twitter.com/chartoftheday