Well, let‘s take a look at your situation. What level are your athletes or clients at? New athletes or clients probably would not benefit from percentages as much as more advanced clients, as they need to learn how to perform the lift correctly first and foremost. Second, a new client will adapt to the exercise so fast that by the next time you perform the exercise, their 1 rep max may be out of date and thus their percentages would be incorrect (if they used to bench 100lbs, but after 2 workouts they can bench 110lbs, that 60% you have them working out as now too low to cause the adaptation you are looking for).
Also, just imagine the amount of paper you would be using all year round just to store all of those data and numbers. You can do Mother Nature a good turn by switching to using electronic spreadsheets instead of manual options. And if it is not the ease of use or the speed of the calculations that you are after, at least you would see the benefit of the automatic formatting features that come with any spreadsheet software. Now you can easily have very presentable spreadsheets done for you as you type your data inside the cells. You do not have to worry too much about the look of your spreadsheets, especially if you are presenting these to your clients. Businesses generally make extensive use of spreadsheets both in accounting and all other business fields. Being a numerically based system of analyzing information spreadsheets are used throughout every accounting function as the technique presents an ideal basis to maintain accuracy and automate the collection of financial information.