That makes absolutely no sense since Apollo and Forest of Fun were grouped in the same sentence. They opened in 1999 and 2009, so clearly BGW wasn't going for "number of seasons." One way or another, the park is wrong- you can't have it both ways.2010 counts as its first year. If you count each year it was in operation, you get 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018. Making 2019 the 10th year it is running.
Same thing applied to HoS; even though 1999 was their first year, 2018 was the 20th season.
Edit: What Nicole said.