Colorado is a state with a population of roughly five million people. There are many hundreds of thousands of court cases in the state each year in which often multiple affidavits or declarations are filed and depositions are taken under oath, there are thousands of evidentiary hearings in the state courts of the state each year, and there are myriad documents executed by its citizens under oath or under penalty of perjury outside a court setting (e.g. in government paperwork).
An intentional false statement of material fact (i.e. a lie) made in testimony made under oath in a hearing, trial or deposition, or in an affidavit or a declaration or other document signed under penalty of perjury, can be prosecuted criminally in a perjury case under state law.
Most of the statements made under oath do not contain perjury, but a significant minority percentage do. Even if perjury were committed just 1% of the time (which is probably low), there would be thousands of instances of perjury committed each year in the State of Colorado.
How many perjury prosecutions were commenced in the entire state of Colorado in all of its state courts (except Denver county court which is statistically separate) in the 2019 fiscal year (ending June 30, 2019)?
There are 5 filed in District Court, which were probably felonies. There were 2 filed in juvenile delinquency actions. There were 6 filed in County Court, which were either misdemeanors or criminal complaints that would later have been transferred to District Court and would be in that case duplicative.
There is no reason to think that plea bargaining rates are significantly different in perjury cases relative to other kinds of criminal cases, so there are probably no more than one or two perjury trials in the entire state of Colorado in a typical year.
Despite the fact that the threat of a criminal prosecution for perjury is a backbone of our court system and many of our administrative and civil legal processes outside of court, perjury prosecutions are almost never brought.
Prosecution practices may differ from state to state, but Colorado is almost always statistically typical, and this is the norm. The threat of criminal prosecution for lying under oath is ever present, but the reality of such a criminal prosecution is almost non-existent.