Looking up events it looks like this is how many events we've had each year:
2012: 2 Events
2013: 7 Events
2014: 6 Events
2015: 6 Events + 1 Historical Questlines
2016: 8 Events + 7 Historical Questlines
2017: 8 Events + 8 Historical Questlines
2018: 8 Events + 5 Historical Questlines
2019: 9 Events
2020: 9 Events
2021: Total amount to be determined
Speaking of Great Buildings, you can now get Wishing Wells from a Great Building
You'd want to hyper level it if you're after Wishing Wells sure, but you can get it.