• The series of Spanish Regional Costumes (Trajes regionales) began with a stamp issued 14 January 1967 (Álava province) and eventually became a long-running series of provincial costume stamps — the article in Linn’s notes the series ran to dozens of stamps (reported as 53 stamps in that overview).
• Spain issued additional batches of provincial/regional costume stamps in the late 1960s and early-1970s — there are documented sets for 1967, 1968, 1969, 1970 and 1971 (lots and dealer listings show year-group lots and individual sets).
• Collectors commonly list these by province/region and by catalogue numbers (Scott / Yvert / SG). Auction/listing sites and specialist catalogs (Yvert listings on collector sites) show individual stamp IDs and maxicards for specific years.

Examples (samples you’ll find)

• 14 Jan 1967 — Álava (first stamp of the run).
• 1968 — sets of 12 provincial costume stamps are recorded in dealer listings.
• 1969 — larger sets (e.g., 12 stamps) and individual provincial issues appear in listings and year sets.
• 1970–1971 — continuing issues and small sets (dealer lots show 1970 and 1971 costume stamps).