D I S A B I L I T Y γ t = S U M H L Y L D W O R K γ t P O P 15 T O 65 γ t {\displaystyle DISABILITY_{\gamma }^{t}={\frac {SUMHLYLDWORK_{\gamma }^{t}}{POP15TO65_{\gamma }^{t}}}}
<math>WORLDDISAVG^t=\frac{WORLDDISABILITY^t}{WORLDWORKPOP^t}