I dont not know and since I did not have a empty bottle to check, a little googling:
Rubbing alcohol is a liquid prepared for topical application to skin usually consisting of isopropyl alcohol with water or with a small admixture of methyl alcohol. Some mixtures use ethyl alcohol in part or whole substitution for iso-propanol.
Rubbing alcohol is poisonous and can cause permanent disabling illness or death if consumed. Rubbing alcohol evaporates quickly and is used to cool and soothe skin. It is also used to sterilize surfaces or, when mixed with only water, clean minor cuts or abrasions. Other mixtures should be used with great caution near cuts or abrasions. It is also occasionally used to harden skin such as in the case of the feet of novice hikers. Care should always be taken, and label of the preparation read carefully.
So yes it appears that it might be diluted, but with what appears to differ based on brand and use. All I can offer is that using the 91% product (around 78 cents at Walmart) and 30% water "on average" works fine for me personally.