Understanding Society User Support

I am looking at the conditions present in the dataset, generally only considering those with hcond or mhcond. However, there is a big change in the number of these from around wave 10 onwards. One of the things I am interested in is researching the changes in multimorbidity over time. However, this increase in number of variables means that, between wave 9 and 10, the number of respondents considered to have two or more conditions dramatically increases.

Do you have any solutions to this?
Thank you