“Business” includes business, profession, and occupation of every kind. A writing or record made in the regular course of business as a memorandum or record of an act, transaction, occurrence, or event is admissible to prove the act, transaction, occurrence, or event. The practice of the business must be to make such written records of its acts at the time they are done or within a reasonable time afterwards. The lack of personal knowledge of the maker of the written notice may be shown to affect the weight of the evidence but not its admissibility.