In a certain population of koalas, one in 2,500 births results in an albino koala. Albino koalas have completely white fur and lack normal pigmentation. The allele that causes albinism is recessive and is a result of a mutation in the TYR gene. According to the Hardy-Weinberg principle, the following equations can be used to estimate allele and genotype frequencies within a population:

$$p^2+2pq+q^2=1$$ $$p+q=1$$

Use the Hardy-Weinberg equations to calculate the percentage of koalas in this population that are heterozygous for the TYR gene. Give your answer to one significant figure. Show your working.