I have read an CSV file from a questionnaire with many non-numeric, nominal values, e.g, country codes, computer skills (Expert, Intermediate, Beginner), … via read.csv I want to have the percentages of each answer for each questions, i.e. , similar to a frequency table given by summary, sorted by occurrences from high to low. Later, I also want to do cross-tabulation, e.g., country with computer skills. `summary(data)` gives me almost what I want, i.e. it gives me a frequency table of the answers, but the frequencies are 1. Not ordered by frequency but by variable 2. Are not percentages. `prop.table` should give percentage tables, but it works only with numeric values. Is there any easy way? Which function can I use?