Bacteria were grown in a medium containing ${}^{15}N$. After several generations, all of the DNA contained ${}^{15}N$. Some of these bacteria were transferred to a medium containing the common isotope of nitrogen, ${}^{14}N$. The bacteria were allowed to divide once. The DNA of some of these bacteria was extracted and analysed. This DNA was all hybrid DNA containing equal amounts of ${}^{14}N$ and ${}^{15}N$.

Some bacteria from the medium with ${}^{15}N$ were transferred into a medium of ${}^{14}N$. The bacteria were allowed to divide twice. The graph shows the percentages of ${}^{14}N$ and ${}^{15}N$ in the DNA of these bacteria.

Some bacteria from the medium with ${}^{15}N$ were transferred into a medium of ${}^{14}N$. The bacteria were allowed to divide three times.

What would be the percentages of ${}^{14}N$ and ${}^{15}N$ in the DNA extracted from these bacteria?