I made it with R, with the code and running results on it. The fitting function is y =1000 * a1* exp (b1* (x-1990)). The estimated values of two parameters A 1 and B 1 are 10.9 and 0. 12, respectively. As can be seen from the summary of the first figure, the p values of both parameters are less than 0.05, which means significant. Of course, we can also use quadratic function fitting and so on.