The age of the Earth is considered as 4.6 billion years. Before the oxygen appeared, the oldest life form was considered to be found around 3.8 billion years ago was the oldest microbe capable of growing and dividing. The appearance of life form is considered to have a relationship with the discovery of the strong absorbing Ultraviolet rays which is in turn related to the hydrocarbon presence.
Taking the above considerations, the percentage of time has life existed on Earth is
{3.8/4.6}*100=82.6 or approximately 83% ,
![(3.8)/(4.6)*100=82.6%](https://img.qammunity.org/2019/formulas/biology/college/cmd696k1axpcvfbu12aytdbziccvcfjlpx.png)