In some cases it is an offense by itself to plan or attempt to commit a crime; this in called an inchoate offense. Examples of inchoate offenses include conspiracy to commit murder and attempted burglary. There can be various causes of failing in the attempt, for example arrest prior to committing the crime.
... 18 to 24, 28.0% from 25 to 44, 25.8% from 45 to 64, and 17.2% who are 65 years of age or older. The median age is 41 years. For every 100 females there are 92.6 males. ...