Hello!

I have four variable ‘education’, year 2000, year, 2005, and year 2010

Education year 2000 year 2005 year 2010
3. 3. 3. 4
2. 2 3. 3
2. 2. 2. 3
1. 1. 2. 3

Which method should I use to «calculate» or to investigate to see if education have changed over the years? Which command can I use here?