Level is calculated after 1989:Q4 benchmark as the previous level, plus net investment in residential structures (FOF series FU115035023), other volume changes, and capital gains. Other volume changes are equal to unpublished BEA data on nonfinancial noncorporate business disaster losses on residential structures (a portion of NIPA, Table 5.1. Saving and Investment, line 60, Disaster losses, Domestic business), with the opposite sign. Capital gains are calculated as the weighted average of single-family house prices (FOF series FI075035243) and multi-family house prices (FOF series FI075035403), where single-family prices are weighted 62 percent and multi-family prices are weighted 38 percent. Data for the past ten years show no significant seasonality.