A sample of a new cleaning product, "Joe's Famous Bleach Cleaner," with a mass of 59.0 g , was diluted with an acetic acid solution containing excess I−. A small amount of starch indicator solution was then added, turning the solution a deep bluish-purple. The solution was then titrated with 0.150 M sodium thiosulfate, Na2S2O3, containing the ion S2O32−. A volume of 40.0 mL of sodium thiosulfate, the titrant, was needed to turn the solution colorless.

What is the percentage composition by mass of NaClO in the bleach product?