A joint survey by two conservation groups, World Conservation Union and the World Wildlife Fund, says the black rhino population has risen to over 3,600. That is an increase of 500 animals over the last two years.
2 years earlier, the black rhino numbered 500.
Actually, the black rhino population has risen to over 3,600 - an increase of 500 over the last two years - when the number would have been around 3100. The math fooled the model.
( z1 number :ARG1 ( z2 rhino :ARG1-of ( z3 black ) ) :ARG2 500 :time ( z4 before :op ( z5 now ) :quant ( z6 temporal-quantity :quant 2 :unit ( z7 year ) ) ) )