Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| National park | Region | Land area (km²) | Established | Visitation (2009) | Coordinates |
| --- | --- | --- | --- | --- | --- |
| Archipelago | Finland Proper | 500 | 1982 | 53,500 | 59°54′53″N 21°52′39″E﻿ / ﻿59.91472°N 21.87750°E |
| Bothnian Sea |  |  | 2011 |  |  |
| Eastern Gulf of Finland | Kymenlaakso | 6.7 | 1982 | 19,000 | 60°17′5″N 27°16′26″E﻿ / ﻿60.28472°N 27.27389°E |
| Ekenäs Archipelago | Uusimaa | 52 | 1989 | 44,500 | 59°49′22″N 23°27′15″E﻿ / ﻿59.82278°N 23.45417°E |
| Helvetinjärvi | Pirkanmaa | 49.8 | 1982 | 33,000 | 62°2′N 23°51′E﻿ / ﻿62.033°N 23.850°E |
| Hiidenportti | Kainuu | 45 | 1982 | 12,000 | 63°52′22″N 29°3′31″E﻿ / ﻿63.87278°N 29.05861°E |
| Isojärvi | Central Finland | 19 | 1982 | 10,500 | 61°41′54″N 25°0′39″E﻿ / ﻿61.69833°N 25.01083°E |
| Kauhaneva-Pohjankangas | Southern Ostrobothnia / Satakunta | 57 | 1982 | 4,500 | 62°10′45″N 22°24′23″E﻿ / ﻿62.17917°N 22.40639°E |
| Koli | North Karelia | 30 | 1991 | 127,500 | 63°3′27″N 29°53′14″E﻿ / ﻿63.05750°N 29.88722°E |
| Kolovesi | Southern Savonia | 23 | 1990 | 7,500 | 62°15′27″N 28°49′0″E﻿ / ﻿62.25750°N 28.81667°E |
| Kurjenrahka | Finland Proper | 29 | 1998 | 28,500 | 60°43′14″N 22°23′1″E﻿ / ﻿60.72056°N 22.38361°E |
| Lauhanvuori | Southern Ostrobothnia | 53 | 1982 | 10,000 | 62°09′7″N 22°10′30″E﻿ / ﻿62.15194°N 22.17500°E |
| Leivonmäki | Central Finland | 29 | 2003 | 12,500 | 61°56′N 26°2′E﻿ / ﻿61.933°N 26.033°E |
| Lemmenjoki | Lapland | 2,850 | 1956 | 10,000 | 68°30′N 25°30′E﻿ / ﻿68.500°N 25.500°E |
| Liesjärvi | Tavastia Proper | 22 | 1956 | 30,500 | 60°40′50″N 23°51′30″E﻿ / ﻿60.68056°N 23.85833°E |
| Linnansaari | Southern Savonia / Northern Savonia | 38 | 1956 | 31,000 | 62°6′38″N 28°30′34″E﻿ / ﻿62.11056°N 28.50944°E |
| Nuuksio | Uusimaa | 45 | 1994 | 179,500 | 60°18′27″N 24°29′57″E﻿ / ﻿60.30750°N 24.49917°E |
| Oulanka | Northern Ostrobothnia / Lapland | 270 | 1956 | 165,500 | 66°22′32″N 29°20′19″E﻿ / ﻿66.37556°N 29.33861°E |
| Päijänne | Päijänne Tavastia | 14 | 1993 | 15,000 | 61°23′12″N 25°23′36″E﻿ / ﻿61.38667°N 25.39333°E |
| Pallas-Yllästunturi | Lapland | 1,020 | 2005 | 419,000 | 68°9′32″N 24°2′25″E﻿ / ﻿68.15889°N 24.04028°E |
| Patvinsuo | North Karelia | 105 | 1982 | 12,000 | 63°6′41″N 30°42′16″E﻿ / ﻿63.11139°N 30.70444°E |
| Perämeri | Lapland | 2.5 | 1991 | 9,000 | 65°37′22″N 24°19′10″E﻿ / ﻿65.62278°N 24.31944°E |
| Petkeljärvi | North Karelia | 6 | 1956 | 19,500 | 62°35′N 31°11′E﻿ / ﻿62.583°N 31.183°E |
| Puurijärvi-Isosuo | Pirkanmaa / Satakunta | 27 | 1993 | 11,500 | 61°14′57″N 22°34′1″E﻿ / ﻿61.24917°N 22.56694°E |
| Pyhä-Häkki | Central Finland | 13 | 1956 | 17,000 | 62°50′44″N 25°28′21″E﻿ / ﻿62.84556°N 25.47250°E |
| Pyhä-Luosto | Lapland | 142 | 2005 | 128,000 | 67°3′59″N 26°58′25″E﻿ / ﻿67.06639°N 26.97361°E |
| Repovesi | Kymenlaakso / Southern Savonia | 15 | 2003 | 74,500 | 61°11′N 26°53′E﻿ / ﻿61.183°N 26.883°E |
| Riisitunturi | Lapland | 77 | 1982 | 15,000 | 66°14′N 28°30′E﻿ / ﻿66.233°N 28.500°E |
| Rokua | Northern Ostrobothnia / Kainuu | 4.3 | 1956 | 23,500 | 64°33′22″N 26°30′36″E﻿ / ﻿64.55611°N 26.51000°E |
| Salamajärvi | Central Ostrobothnia / Central Finland | 62 | 1982 | 10,500 | 63°16′N 24°45′E﻿ / ﻿63.267°N 24.750°E |
| Seitseminen | Pirkanmaa | 45.5 | 1982 | 45,500 | 61°56′N 23°26′E﻿ / ﻿61.933°N 23.433°E |
| Sipoonkorpi | Uusimaa | 18.6 | 2011 |  | 60°18′54″N 25°13′8″E﻿ / ﻿60.31500°N 25.21889°E |
| Syöte | Northern Ostrobothnia / Lapland | 299 | 2000 | 40,000 | 65°44′51″N 27°54′43″E﻿ / ﻿65.74750°N 27.91194°E |
| Tiilikkajärvi | Northern Savonia / Kainuu | 34 | 1982 | 7,500 | 63°40′N 28°18′E﻿ / ﻿63.667°N 28.300°E |
| Torronsuo | Tavastia Proper | 25.5 | 1990 | 20,500 | 60°44′N 23°37′E﻿ / ﻿60.733°N 23.617°E |
| Urho Kekkonen | Lapland | 2,550 | 1983 | 289,000 | 68°13′5″N 28°8′25″E﻿ / ﻿68.21806°N 28.14028°E |
| Valkmusa | Kymenlaakso | 17 | 1996 | 7,000 | 60°34′N 26°44′E﻿ / ﻿60.567°N 26.733°E |
Question:
what is the number of national parks that have a landmass of under 50 square km?
Answer:
23