Question: How many characters is typically used in the runic alphabet found on 30 runestones that refer to Viking Age travels to England?

Context paragraphs:
Manx runestones: The Manx runestones were made by the Norse population on the Isle of Man during the Viking Age, mostly in the 10th century.  Despite its small size, the Isle of Man stands out with many Viking Age runestones, in 1983 numbering as many as 26 surviving stones, which can be compared to 33 in all of Norway.  So many of them may appear on the Isle of Man because of the merging of the immigrant Norse runestone tradition with the local Celtic tradition of raising high crosses.

Seax of Beagnoth: The Seax of Beagnoth (also known as the Thames scramasax) is a 10th-century Anglo-Saxon seax (single-edged knife).  It was found in the River Thames in 1857, and is now at the British Museum in London.  It is a prestige weapon, decorated with elaborate patterns of inlaid copper, bronze and silver wire.  On one side of the blade is the only known complete inscription of the twenty-eight letter Anglo-Saxon runic alphabet, as well as the name "Beagnoth" in runic letters.  It is thought that the runic alphabet had a magical function, and that the name Beagnoth is that of either the owner of the weapon or the smith who forged it.  Although many Anglo-Saxon and Viking swords and knives have inscriptions in the Latin alphabet on their blades, or have runic inscriptions on the hilt or scabbard, the Seax of Beagnoth is one of only a handful of finds with a runic inscription on its blade.

Younger Futhark: The Younger Futhark, also called Scandinavian runes, is a runic alphabet and a reduced form of the Elder Futhark, with only 16 characters, in use from about the 9th century, after a "transitional period" during the 7th and 8th centuries.

Stenkvista runestone: The Stenkvista runestone, designated as runic inscription Sö 111 in the Rundata catalog, is a memorial runestone located near the church at Stenkvista, which is two kilometers east of Skogstorp, Södermanland County, Sweden, which was formerly part of the historic Södermanland, and which features a depiction of Thor's hammer, Mjöllnir.  This runestone is one of several runestones in Scandinavia that has a dedication to Thor.  While the tradition of carving inscriptions into boulders began in the 4th century and lasted into the 12th century, most runestones in Scandinavia date from the late Viking Age.

Runestone: A runestone is typically a raised stone with a runic inscription, but the term can also be applied to inscriptions on boulders and on bedrock.  The tradition began in the 4th century and lasted into the 12th century, but most of the runestones date from the late Viking Age.  Most runestones are located in Scandinavia, but there are also scattered runestones in locations that were visited by Norsemen during the Viking Age.  Runestones are often memorials to dead men.  Runestones were usually brightly coloured when erected, though this is no longer evident as the colour has worn off.

Södermanland Runic Inscription 194: Sö 194 is the Rundata designation for a runic inscription on a memorial runestone located in Brössike, which is about 12 kilometers northeast of Strängnäs, Södermanland County, Sweden, which was in the historic province of Södermanland.  There are many such memorial runestones in Scandinavia.  While the tradition of carving inscriptions into boulders began in the 4th century and lasted into the 12th century, most runestones date from the late Viking Age.

Gällsta Runestones: The Gällsta Runestones from the 11th century commemorate four generations of the same family in Viking Age Sweden.  There are three runestones (U 229, U 231 and U 232) and a raised stone which is only inscribed with a cross (U 230).  The runestones are located at the northern outskirts of Stockholm, just northwest of the lake Vallentunasjön, around which is found the world's greatest concentration of runestones.  All the Gällsta Runestones are attributed to Öpir, the most productive of all the old runemasters.

Greece runestones: The Greece runestones (Swedish: "Greklandsstenarna", Greek: "Ρουνικές λίθοι Ελλάδας") are about 30 runestones containing information related to voyages made by Norsemen to the Byzantine Empire.  They were made during the Viking Age until about 1100 and were engraved in the Old Norse language with Scandinavian runes.  All the stones have been found in modern-day Sweden, the majority in Uppland (18 runestones) and Södermanland (7 runestones).  Most were inscribed in memory of members of the Varangian Guard who never returned home, but a few inscriptions mention men who returned with wealth, and a boulder in Ed was engraved on the orders of a former officer of the Guard.

Kyrkogården Runestones: The Kyrkogården Runestones are three Viking Age memorial runestones located at the cemetery of St. Mary's Church in Sigtuna, Stockholm County, Sweden, in the historic province of Uppland.  One of the runic inscriptions documents the existence of a Viking Age mercantile guild in Sweden.

England runestones: The England runestones (Swedish: "Englandsstenarna") is a group of about 30 runestones that refer to Viking Age voyages to England.  They constitute one of the largest groups of runestones that mention voyages to other countries, and they are comparable in number only to the approximately 30 Greece Runestones and the 26 Ingvar Runestones, of which the latter refer to a Viking expedition to the Middle East.  They were engraved in Old Norse with the Younger Futhark.

Supporting paragraphs: England runestones Younger Futhark
Answer: 16 characters