Use this:
awk -F'[=s]' '/method1/{t+=$2;c++}END{printf "%ss\n",t/c}' file
-F[=s] sets the field delimiter to = or s making it easy to extract the numerical value between them. t+=$2 will add the numerical value to the total t. c++ will count the lines containing the term method1. After the last line of input has been processed END, we print the total t divided by c, the number of lines containing method1.
Note: Initialization of the variables c and t is not necessary since awk initializes them with 0 on their first usage.